The present invention relates to a fuel-air regulating system for hot gas engines, in which the high temperature level of the working gas is allowed to vary between fixed upper and lower limits with small deviations above and below a predetermined temperature.
The working principle of the hot gas engine is based on the concept of compressing an enclosed volume of gas at a reduced temperature and expanding it at relatively elevated temperatures. In practice, certain engine parts are continuously heated by an external heat source, while other engine parts are being continuously cooled, the gas volume oscillating between said parts during its passage through a regenerator.
A change of the engine power output brings about a corresponding change of the heat transfer. Consequently, a decrease of the engine power output results in a temperature increase in the hot parts of the engine.
From efficiency point of view it is desirable to keep the elevated temperature level of the engine as high as the construction materials permit. Consequently, a temperature increase above a predetermined optimum level must produce a rapid decrease of the external heat supply, and, conversely, a temperature decrease below a predetermined minimum level must result in an increase of the heat flow.
Normally, the heat is generated from the combustion of a fuel and air. The fuel-air regulating system must be constructed with consideration to the above mentioned requirements, and it constitutes an important factor in production costs of the engine.